Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 290901
SWOD48
SPC AC 290900

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT THU SEP 29 2016

VALID 021200Z - 071200Z

...DISCUSSION...
THE OVERALL SEVERE-WEATHER POTENTIAL REMAINS LOW DURING THE LATTER
PART OF THE WEEKEND /DAY 4-SUN/...WITH SOME INCREASE FOR SEVERE
STORMS ACROSS PORTIONS OF THE NORTHERN HIGH PLAINS ON DAY
5-MON...AND A GREATER POTENTIAL INTO DAY 6-TUE ACROSS PORTIONS OF
THE SOUTHERN PLAINS.

00Z ECMWF/GFS/UKMET ARE IN GENERAL AGREEMENT WITH THE INLAND
MOVEMENT OF A PACIFIC TROUGH THROUGH DAY 5...WITH THIS SYSTEM MOVING
INTO CA/NV ON SUNDAY AND THEN ACROSS THE GREAT BASIN...AND EXTENDING
FROM WY/CO TO AZ/NM BY 04/12Z.  ALTHOUGH MODELS TEND TO AGREE WITH
THE PRIMARY PORTION OF THE PROGRESSIVE TROUGH MOVING INTO THE
CENTRAL/NORTHERN PLAINS ON DAY 6-TUE...THE ECMWF/GFS DIFFER IN THE
AMPLIFICATION OF A BASAL SHORTWAVE TROUGH TRACKING ACROSS THE
SOUTHERN HIGH PLAINS TUESDAY AFTERNOON TO OK/KS TUESDAY NIGHT.

...DAY 5/MON...
LEE CYCLONE DEVELOPMENT IS FORECAST ACROSS WY ON MONDAY AS HEIGHTS
FALL DOWNSTREAM OF THE PRIMARY MIDLEVEL TROUGH CROSSING THE GREAT
BASIN TO THE CENTRAL/SOUTHERN ROCKIES.  THIS SURFACE LOW IS EXPECTED
TO MOVE INTO WESTERN SD BY 04/12Z. MARGINAL INSTABILITY ACROSS
PORTIONS OF THE NORTHERN HIGH PLAINS INTO WESTERN PORTIONS OF
ND/SD/NEB COULD SUPPORT A FEW STRONG TO SEVERE STORMS MONDAY
AFTERNOON AND EVENING...THOUGH COVERAGE IS NOT EXPECTED TO BE
SUFFICIENT TO INCLUDE A 15 PERCENT SEVERE-PROBABILITY AREA.

...DAY 6/TUE...
MODELS DIFFER IN THE AMPLITUDE OF THE AFOREMENTIONED BASAL SHORTWAVE
TROUGH MOVING THROUGH THE SOUTHERN HIGH PLAINS TUESDAY AFTERNOON.
HOWEVER...THERE IS AGREEMENT WITH THE ECMWF/GFS FOR A RELATIVELY
NARROW CORRIDOR OF MODERATE INSTABILITY EXTENDING FROM WESTERN KS
THROUGH WESTERN OK...AND THE TX PANHANDLE TO SOUTHWEST TX.  STORM
DEVELOPMENT WILL BE POSSIBLE ALONG THE DRY LINE...WITH CAPE/SHEAR
PARAMETER SPACE SUGGESTING SUPERCELLS WILL BE POSSIBLE.

..PETERS.. 09/29/2016


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